Automatic control system



Feb. 14, 1939. w. 1. BENDZ 2,147,422

AUTOMATIC CONTROL SYSTEM Filed Nov 6, 1937 Fly.

WITN SSESI INVENTOR Wa/a emar Ifiendz.

Patented Feb. 14, 1939 2,147,422

UNITED STATES PATENT OFFICE AUTOMATIC CONTROL SYSTEM Waldemar I. Bendz, Arlington, Mass., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a. corporation of Pennsylvania Application November 6, 1937, Serial No. 173,201

6 Claims. (Cl. 25041.5)

My invention relates to automatic control sysderstood from the following description of a spetems, and it has particular relation to liquid cific embodiment, when read in connection with level control. the accompanying drawing, in which In one of its more specific aspects, my inven- Figure 1 is a diagrammatic view showing the tion is also designed to provide an improved apessential elements of a circuit connected in ac- 5 paratus for pumping sewage either solid or liquid cordance with my invention; and

from filtration tanks in which the solid matter is Fig. 2 is a view in section showing the distinallowed to settle from the liquid matter. guishing feature of a modification of my inven- An object of my invention is to provide an eftion. 0 ficient apparatus for this purpose which will op- The apparatus shown in the drawing comprises crate to start a motor mechanically connected a motor I mechanically connected to a pump 3 with a pump when the liquid in the tank rises used to eject a liquid 5 from a container 1. The above a predetermined maximum level and will motor I may be energized by closing a plurality stop the motor when the water falls below a preof contacts 9 of a line switch H. The motor is determined minimum level. supplied from a suitable three-phase source of Another object of my invention is to start the energy (not Show through the usual line operation of a pump at a predetermined time afductors l3, l5, and I1. Conductors l9 and 2| ter the liquid in a container reaches a predetersupply energy to the control circuit from the mined level and to stop the operation of the pump energized line conductors l5 and I3, respectively. at a predetermined time after the liquid has A photo-sensitive device 23 specifically shown 20 reached a second predetermined level. as a photo-voltaic cell, is electrically connected An ancillary object of my invention is to provide to energize the operating coil 25 of a sensitive an eificient system for intermittently operating a relay 2'! When t i tur s pp W a a t motor or a valve. energy from a source 29, such as an incandescent 25 More specifically stated, it is an object of my lamp. Similarly, another photo-sensitive device 2 invention to eliminate as far as possible any un- 3| is connected to energiz t Operating 0011 33 necessary starting and stopping of a motor in of a second sensitive r y 3 When it has been general in any system in which it is subjected to energized from anoth So e Of a an e e y intermittent loads and in particular in a system 3 W e a p otoevol i l is herein ShOWh in which a pump is operated. as used, it will be understood that any suitable 3 According to my invention, I provide a liquid phete-eleetl'ie e c Such as e p -C and level control system comprising two photo-clecn mp fi a Selenium Cell y he usedtric devices, mounted at two diiierent heights so h Container 1 is provided W a S a that they can be energized by a suitable beam of a portion Of which is transparent- The 35 radiant energy, preferably a light beam. A liquid side arm is so connected to the remaining portion 35 level indicator is disposed to interrupt the light of e Container that the liquid in it Will be mainbeam and thus deenergize the photo-electric cirtained at the same level as t e liquid in t e concuits as the liquid rises to predetermined heights tain Th side a 39 is positioned between the in the container or reservoir. The control circuit light so 29 and 37 and the D ee 40 is so arranged that the pump starts to operate v c 23 a The light beams are P j d 40 at a predetermined time after both photo-electric through the transparent Portion of e S de arm circuits have been deenergized and the pump stops and may be cep y e quid as it rises a predetermined time after both photo-electric in the circuits have been energized. An advantage of t is t be t d at my invention is n n way the time delay is that it eliminates hunting or restricted to the side arm arrangement. The 45 any unnecessary starting and stopping of th liquid 5 in the main portion of the container I motor that may be caused by a too short i t rmay itself be used to actuate the photo-electric ruption of the light beam, such as a disturbance devices, In such a case, the container i proon the surface of the liquid. vided with a transparent section in the wall 43 and The novel features that I consider characterh s r d photo-electric devices are p op- 5 istic of my invention are set forth with particuerly located on both sides of the p e t porlarity in the appended claims. The invention ittion, th light ou s and the P t -electric self, however, both as to its organization and its devices protected by suitable watertight housings method of operation, together with additional mounted as an adjustable unit may be immersed objects and advantages thereof, will best be undirectly in the liquid in the container. Also, un- 55 this time may be sufficient to cause this undeder certain conditions, it may be desirable to use a float either in the container or in the side arm to intercept the light beams or to otherwise initiate the functioning of the control circuit.

The sensitive relays 25 and 33 function to actuate auxiliary relays 95 and ii, respectively, which in turn actuate a time delay relay 49. While the time delay relay shown in the drawing is of the dash-pot type, it is understood that a time delay relay of any well known type, may

be utilized. For example, a motor operated timer may be used in lieu of the dash-pot relay. The time delay relay 49 is so connected in the circuit that it delays the starting and the stop ping of the pump until it has remained energized for a predetermined time interval. Two time delay relays may be utilized for this purpose, one to delay the starting of the pump and the other to delay the stopping of the pump. It will also be understood that only one time delay relay may be used to delay either the starting of the pump alone or the stopping alone.

Assume that the liquid in the container has been rising for some time and that its level is such that the light beam from the upper source 29 passes through the transparent portion ll of the side arm 39 of the container 1 and impinges on the upper photoeelectric device 23 while the other light beam is intercepted by the liquid. In

such a case, the upper sensitive relay 2? is energized and the lower sensitive relay 35 is deenergized and the system is in the condition shown in the drawing.

When the liquid rises high enough to intercept the light beam from the upper light source 29, the illumination impinged on the upper photoelectric device 23 is reduced and the first sensitive relay 2'! is deenergized. Its contacts 5| close a circuit extending from the energized conductor |9 through the contacts 5| of the first sensitive relay 2?, the operating coil 53 of the first auxiliary relay 45 to the other energized conductor 2|.

The operating coil 53 thereby functions to close the contacts 55 and 5? of the first auxiliary relay 45. The upper contacts 55 complete the circuit for energizing the operating coil 59 of the timing relay 39 which extends from the energized conductor l9 through operating coil 59 of timing relay 49 and the closed contacts 55 of the first auxiliary relay 45 to the other energized conductor 2|. When the operating coil 59 has remained energized for an interval of' time determined by the condition of the relay 49, the contacts 6| are closed.

Should the level of the liquid 5 in the side arm 39 drop to such an extent that the upper light beam again impinges on the upper photo-electric device 23 before the timing relay 49 functions, the first sensitive relay 2? would be reenergized, opening contacts 5| to deenergize the first auxiliary relay 45, thus opening the circuit to the operating coil 59 of the timing relay 49. To reestablish the circuit through the operating coil 1 of the timing relay 49, it is necessary for the liquid to rise again to intercept the light beam impinged on the upper photo-electric device 23. The operation of the first sensitive relay 21, the first auxiliary relay 45, and the-time delay relay 49 will thus be repeated as described hereinabove until the timing relay has been energized for a predetermined time interval. Any disturbance that would agitate the liquid in the container at sirable operation. The timing relay will'thus protect the line switch and the motor from any unnecessary operations.

The contacts 6| of the timing relay when it is finally energized establish a circuit for a starting relay 63 which extends from the energized conductor I9 through the closed contacts 5| of the timing relay 99, the operating coil 65 of the starting relay 53 and the previously closed lower contacts 5'5 of the first auxiliary relay 45 to the other energized conductor 2|. This completes the circuit through the operating coil 61 of the line switch thus closing the main contacts 9 to energize the motor and start the operation of the pump 3. The circuit to the operating coil 67 of the line switch extends from the energized conductor 9 through the operating coil 61, the normally closed contacts 69 of a stopping relay 1| and the closed contacts 13 of the starting relay 63 to the other energized conductor 2|.

As the pump 3 operates to eject the liquid 5 from the container 1, the level of the liquid in the side arm 39 begins to fall. When the liquid no longer intercepts the upper light beam, the upper photo-electric device 23 functions to energize the first sensitive relay 21, thus deenergizing the first auxiliary relay 45 which cleenergizes the time delay relay 49 and the starting relay 63.

However, the line switch remains in the energized condition because the closed auxiliary conand the closed auxiliary contacts 15 of the line switch II to the other energized conductor 2|. The level of the liquid 5 continues to fall as the pump 3 operates.

When the light beam from the lower light source 3'! is no longer intercepted by the liquid in the transparent portion 4| of the side arm 39, the lower photo-electric device 3|. becomes illuminated, thereby energizing the operating coil 33 of the second sensitive relay 35.

The second sensitive relay 35 functions to close contacts Ti to energize the operating coil 19 of the second auxiliary relay 47. This circuit extends from the energized conductor I9 through the closed contacts I! of the second sensitive relay and the operating coil 19 of the second auxiliary relay 9?, to the other energized conductor 2|. The second auxiliary relay is then actuated to close the contacts 8| and 83. ;The upper contacts 8| of the second auxiliary relay 91 complete the circuit through the operating coil 59 of timing relay 99. This circuit extends from the energized conductor 9 through the operating coil 59 of timing relay 49 and the closed upper contacts 8| of the second auxiliary relay 4-1. After a predetermined time interval, timing relay functions to close contacts 6|.

Before the timing relay 49 functions, it is possible that the liquid may be entering the container at substantially the same rate at which it is being ejected by the pump, or the liquid may suddenly enter the container at a faster rate. Should this happen, the liquid in the side arm 39 will rise to interceptthe lower light beam thereby-deenergizing the second auxiliary relay 55 which thus deenergizes the time delay relay 49 and prevents the operation of the stopping relay 7!. A slight disturbance on the surface of the liquid in the container may also be sufiicient to cause this operation.

When the level of the liquid again enough for the light beam from the lower light source 31 to impinge on the lower photo-electric device 3I the second sensitive relay 35, the second auxiliary relay 4'! and the timing relay 49 will function as described hereinabove. After the operating coil 59 of the timing relay 49 has been energized for a predetermined interval of time, the contacts 6| will close to complete the circuitthrough the operating coil 85 of the stopping relay II.

This circuit extends from the energized conductor I9 through the contacts 6!, the operating coil 85 and the closed lower contacts 83 of the second auxiliary relay 4! to the other energized conductor 2|. The contacts 69 of the stopping relay II function to open the circuit through the operating coil 6'! of the line switch It. The line switch is then actuated to open the main contacts 9, thus deenergizing the motor I and stopping the operation of the pump 3. The circuit through the upper contacts 15 of the line switch H is also opened. The circuit through the operating coil of the line switch is thus maintained in the open condition until a predetermined time after the upper photo-electric device 23 has properly functioned.

When the pump is not operating, the level of the liquid will again begin to rise. As the liquid rises it will again interrupt the light beam from the lower light source 3! thus actuating the lower photo-electric device 3| to deenergize the second sensitive relay 35. The second sensitive relay 35 operates to open contacts ll thus deenergizing the second auxiliary relay 41. The second auxiliary relay functions to open contacts BI and 83 which open the circuit to operating coil 59 of. timing relay 49 and the circuit to the operating coil 85 of stopping relay ll, respectively. Stopping relay 'II functions to close contacts 69 thus partially reestablishing the circuit through the operating coil 61 of the line switch I The circuit is so changed that it again assumes the condition shown in the drawing. The above-described cycle can be repeated indefinitely as the liquid continues to rise in the container.

The circuit arrangement explained hereinabove may be modified in various ways to accomplish somewhat the same result. For example if the photo-electric devices are capable of supplying sufiicient power or their output is sufficiently amplified to directly operate more rugged relays similar to the starting relay 63 and the stopping relay II the auxiliary relays may be eliminated. Further, if the relays now controlled directly by the photo-electric devices are each provided with a time delay element, the separate time delay relay may be eliminated. Assuming that relays 21 and 35 are of the same rugged type as relay 63 and 85, the contacts 13 may be replaced in the control circuit by contacts and operating coil 35 may be replaced by operating coil 33. With this change the operating coils 53, 59, 53, I9 and 85 and the contacts 55, 51, BI, 13, 11, BI and 83 may be eliminated.

It is to be noted that while my invention has been shown herein as specifically applied to a pump control system for ejecting a liquid from a container, it will be evident to those skilled in the art that it has other applications. In general, it may be said that my invention can be applied to control the supply of power from a power source to any work circuit. As regards to other applications for pump control systems, my invention can be used to control a pump or valve used to control the supply of a liquid or any other suitable substance to a container. Another application may be to control the removal of sediment I05 from a settling tank 'I such as used in a sewage treatment plant and illustrated in Fig. 2. In this application the sewage 5 flows into the tank, the sediment or sludge I55 settles to the bottom of the tank while a substantially clear liquid 95 flows out at the top of the tank. For the most eificient operation, it is desirable to maintain the sediment I 05 at a substantially constant height in the settling tank I. The sediment or sludge at the bottom of the tank and the sub stantially clear liquid at the top of the tank are characterized by a marked difference in opacity. Because of this property of the liquids, the pump 3 may be controlled in the manner hereinabove described. The light sources 29 and 3i and the photo-electric devices 23 and 3! are mounted Within the tank so that the light beams may be interrupted by the sediment in the bottom of the tank. The light sources 29 and 3! and the photoelectric devices 23 and 3|, enclosed in watertight housings, are assembled as a unit preferably on a pipe structure 9! and mounted within the tank I so that the light beams may be inter-- rupted by the sediment I85 in the bottom of the tank. The entire unit may be adjusted to the desired height in the tank or readily raised to the top of the tank for periodic inspection and cleaning. The connections from the light sources 29 and 3? and the photo-electric devices 23 and 3| to the relay cabinet are made through the pipe structure 91. The light beam from the upper light source 29 determines the high level of the sediment I65 and controls the starting of the pump 3, and the light beam from the lower light source 31 determines the low level of the sediment and controls the stopping of the pump 3. The time delay relay 49 is desirable because of the turbulence of the sludge. Turbulence may be caused by any disturbance at the surface of the sludge or sediment. For example when the pump is operating the movement of the sludge in the tank may at times cause enough disturbance to cloud up the liquid near the photo-sensitive devices and thus produce operation which would not otherwise be produced. The liquid emptied into the tank may cause a disturbance at the surface of the sludge or it may contain enough sedimentary matter to cloud up the liquid in the container. It is understood that the photo-sensitive devices may be so positioned with respect to the inlet and outlets of the container that they will be least aifected by turbulence.

I do not wish to be restricted to the specific structural details, arrangement of parts or circuit connections herein set forth, as various modifications thereof, may be eifected Without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. Translating apparatus comprising a controller, a pair of photo-electric devices for controlling the operation of the said controller, means for varying the excitation of the said pair of photo-electric devices in a predetermined manner to actuate the said controller, a time delay relay cooperating with the said pair of photo-electric devices and the said controller to delay the actuation of the said controller a predetermined time after either of the said. pair of photo-electric devices has functioned.

2. Translating apparatus comprising a controller, a pair of photo-electric devices for con- 7 trolling the operation of the said controlled means for varying excitation of the said pair of photo-electric devices in a predetermined manner to actuate the said controller, a time delay relay cooperating with the said pair of photo-electric devices and the said controller to delay the actuation'of the said controller a predetermined time after either of the said pair of photo-electric devices has functioned, means for rendering either of the said pair of photo-electric devices ineffective to actuate the said controller after it has functioned in a predetermined manner, and means for maintaining the said photo-electric device ineffective to actuate the said controller until after the other of the said pair of photoelectric devices has functioned to actuate the said controller, means for deenergizing the said time delay relay after it has properly functioned in cooperation with either of the said pair of photoelectric devices, and means for'rendering it effective to function in cooperation with the other of the said pair of photo-electric devices.

3. A system for controlling the application of power from a power source to a work circuit in response to a condition that changes and persists as changed for relatively long intervals of time, fluctuating changes of said condition being simultaneously superimposed on the said long changes, comprising means for coupling and uncoupling the said power source to and from the said work circuit, a first device sensitive to radiant energy, a second device sensitive to radiant energy, means alternately responsive to the said first and the said second devices to actuate the said coupling and uncoupling means a predetermined time, shorter than the said long intervals of time and substantially longer than the said short intervals, after either the said first device or the said second device has functioned for a predetermined condition.

4. Translating apparatus comprising a controller, a pair of devices that are actuated in response to the presence of a physical disturbance for controlling the operation of the said controller, means for varying the excitation of the said pair of devices in a predetermined manner to actuate the said controller, a timing means cooperating with the said pair of devices and the said controller to delay the actuation of the said controller a predetermined time after either of the said pair of devices has functioned.

5. In combination a first and second set of selective contacts to be closed in response to a first physical condition, a set of timing contacts actuated a predetermined time after the said first set of selective contacts has functioned, a set of starting contacts to be actuated in response to the said timing contacts and the said second set of selective contacts, a translating device actuated in a first predetermined manner by the said set of starting contacts, a set of holding contacts associated with the said translating device in such a manner that they maintain the translating device in its newly acquired condition regardless of any change in the said first physical condition, a third and a fourth set of contacts to be closed in response to a second-physical condition, the said set of'timing contacts being actuated a predetermined time after the said third set of selective contacts has functioned, a set of stopping contacts to be actuated in response to the said timing contacts and the said fourth set of selective contacts to actuate the said translating device in a second predetermined manner, and thus to actuate the said holding contacts in such a manner that the said translating device is maintained in its newly acquired condition regardless of any change in the second physical condition.

6. In combination a first set and a second set of contact means disposed to be actuated in response to a first predetermined physical condition, a third set and a fourth set of contact means disposed to be actuated in response to a second predetermined physical condition, a fifth set of contact means connected in circuit relation with the said second set and the said fourth set of contact means and disposed to be actuated a predetermined time after the said first set of contact means has been actuated or a predetermined time after the said third set of contact means has been actuated, a sixth set of contact means disposed to be actuated after the said second set and the said fifth set of contact means have been actuated, a seventh set of contact means disposed to be actuated after the said fourth set and the said fifth set of contact means have been actuated, a translating device disposed to be actuated in a first predetermined manner by the said sixth set of contacts and disposed to be actuated in a second predetermined manner by the said seventh set of contacts and an eighth set of contact means connected in circuit relation with the said sixth set and the said seventh set of contact means and disposed to maintain the first predetermined manner of actuation of the translating device regardless of any change in the said first physical condition.

WALDEMAR I. BENDZ. 

